Breaking News: Tube Stations Evacuated

Reports are coming in from London of what British Transport Police are referring to as three "incidents" at three London Underground stations.

Emergency services rushed to the subway stations on Thursday afternoon, two weeks after bomb attacks killed 56 people.

London's police chief said there were four explosions in London, but a low number of casualties. He added that the bombs or detonations appeared to be smaller than those used in the July 7 attacks. While he said police were treating the situation as very serious, they did not believe it is a major incident on a par with the attacks two weeks ago.

Warren Street, Shepherd's Bush and Oval stations have been evacuated and smoke has been seen coming from one of the stations. Emergency services are at the three scenes.

Ivan McCracken, an eye witness, told Sky News that "people were panicking. But very fortunately the train was only 15 seconds from the station" and he added that he had smelled smoke. Services on the Victoria and Northern lines were suspended following reports of a number of incidents, London Underground said.

There are no reports of casualties as yet and no official explanation has been given. The London police department says not treating emergencies as "major incident yet."

Transport chiefs closed three Underground lines but the rest of the network was open, a spokesman told Reuters. He said they were not shutting the entire network.

"Three lines have been shut but the network is not shutting down," the spokesman said. He said the closed lines were the Hammersmith and City, Victoria and Northern lines.

The shutdowns have caused chaos on the city's already overburdened subway system.

Bus explosion

There were also reports of an explosion on a bus in the
Hackney area of east London. An explosion blew out the
windows of a bus in the Hackney area of London on Thursday but there were no reports of injuries, bus operator Stagecoach said.

"The driver heard a bang he believed came from the upper
desk of the bus. The windows were blown out. There are no reports of any injuries," a Stagecoach spokesman said.

The No. 26 bus was travelling from Waterloo to Hackney in the east of city. The incident occured in the Shoreditch area, the spokesman said. He said the structure of the bus was intact but some windows were blown out.

Smell of smoke

A man travelling on a London underground train on Thursday told Sky News he had smelled smoke and been told by other passengers that a backpack had exploded. He said he had not seen or heard the explosion, but had smelled smoke as the train pulled into a station and passengers disembarked.

One hospital, near Warren Street station, has started its emergency plan.

Sosiane Mohellavi, 35, was travelling from Oxford Circus to Walthamstow when she was evacuated from a train at Warren Street.

"I was in the carriage and we smelt smoke - it was like something was burning," she told the BBC.

"Everyone was panicked and people were screaming. We had to pull the alarm. I am still shaking."

More to follow as additional details become available.